Hydraulic power trim and power tilt system for a marine propulsion device

ABSTRACT

Disclosed herein is an outboard motor including a first extensible hydraulic cylinder means pivotally connected between a transom bracket and a swivel bracket to afford power tilting and, in response to the striking of an underwater obstacle, to afford energy absorption, together with a second extensible hydraulic cylinder means having an extensible part and mounted on the transom bracket with the extensible part positioned for engagement with the swivel bracket to afford trim adjustment. The disclosed outboard motor also includes connection of the first and second extensible hydraulic cylinder means in parallel relation to an electrically operated reversible hydraulic pump and further includes an electrically operated normally closed valve controlling communication between the trimming hydraulic cylinder means and the hydraulic pump independently of the communication between the tilting hydraulic cylinder means and the hydraulic pump, together with a tilt control switch operable to actuate the hydraulic pump, and a trim control switch operable to actuate the hydraulic pump and to open the normally closed valve.

United States Patent 1 Carpenter [451 Mar. 27, 1973 [75] Inventor: Eugene C. Carpenter, Galesburg, Ill.

3,061,250 10/ 1962 Conover ..248/4 3,406,652 lO/l968 Mett, Jr. et a1. ....1 15/41 R 3,434,448 3/1969 Woodfill ..1 15/41 R Primary Examiner-Milton Buchler Assistant Examiner-Carl A. Rutledge Attorney-Robert E. Clemency, John W. Michael,

Gerrit D. Foster, Bayard H. Michael, Paul R. Puerner, Joseph A. Gemignani, Andrew 0. Riteris, Robert K. Gerling and Spencer B. Michael [57] ABSTRACT Disclosed herein is an outboard motor including a first extensible hydraulic cylinder means pivotally connected between a transom bracket and a swivel bracket to afford power tilting and, in response to the striking of an underwater obstacle, to afford energy absorption, together with a second extensible hydraulic cylinder means having an extensible part and mounted on the transom bracket with the extensible part positioned for engagement with the swivel bracket to afford trim adjustment. The disclosed outboard motor also includes connection of the first and second extensible hydraulic cylinder means in parallel relation to an electrically operated reversible hydraulic pump and further includes an electrically operated normally closed valve controlling communication between the trimming hydraulic cylinder means and the hydraulic pump independently of the communication between the tilting hydraulic cylinder means and the hydraulic pump, together with a tilt control switch operable to actuate the hydraulic pump, and a trim control switch operable to actuate the hydraulic pump and to open the normally closed valve.

16 Claims, 6 Drawing Figures PATE T 3.722.455

' SHEET 3 BF 3 9m: C Qrpezter HYDRAULIC POWER TRIM AND POWER TILT SYSTEM FOR A MARINE PROPULSION DEVICE BACKGROUND OF THE INVENTION The invention relates generally to marine propulsion devices such as outboard motors and stern drive units which include vertically tiltable propulsion or lower units supporting a propeller. Such lower units are desirably trimmed relative to the boat and thereby to the water to obtain maximum speed and safety conditions. Such trimming effects both the relation of the boat to the water and the angle at which the propeller generates propulsive thrust. Other factors are involved in the trim of a boat as, for instance, passenger loading and sea conditions. Thus, one particular relationship of a propulsion unit to a boat can give good results under one set of conditions and less satisfactory results under another set of conditions. Furthermore, conditions can change when underway, as for instance, ifthe weather or sea conditions change, or if the distribution of passenger weight changes. Accordingly, it is desirable to be able to adjust the trim under way.

It should also be noted that proper trim between a lower unit and a boat is an important safety factor when under way. In this regard, for instance, a bow-down" condition can cause violent uncontrollable action in swells.

In addition to trim, another factor of significance with respect to vertically tiltable marine propulsion lower units is capability to absorb shock incident to rearward and upward swinging occurring in response to the striking of an underwater obstacle and the capacity for power tilting of the propulsion unit upwardly and downwardly relative to the trimmed running position. For example, propeller removal is facilitated by tilting the lower unit to its fully raised position and shallow water operation at reduced speeds is facilitated by .tilting the lower unit to a partially raised position. Power tilting in the down or return direction also affords return of the propulsion unitafter thestriking of an underwater obstacle and after power tilting upwardly'to partially and fully raised positions.

Various arrangements have been provided in the past for hydraulically absorbing shock or dissipating energy in response to the striking of an underwater obstacle. In addition, various arrangements have been employed to afford power tilting of a marine propulsion lower unit between a running position and a partially or fully raised or elevated position. In addition, various hydrau- Iic arrangements have been provided for adjusting the trim of an outboard motor relative to a boat even when under way and'to afford energy absorption in response to striking of an underwater obstacle. However, all the known prior arrangements were incapable, without trim setting by the operator, of affording propulsion unit return to the same trim position after power tilting or after tilting in response to the striking of an underwater obstacle. The Examiner's attention is directed to the following United States patents: Ziegler U.S. Pat. No. 3,250,240 issued May 10, 1966; Kiekhaefer U.S. Pat. No. 2,953,335 issued Sept. 20, 1960; North U.S. Pat. No. 3,295,221 issued Nov. 15, 1966; North U.S. Pat. No. 3,434,449 issued Mar. 25, 1969; Woodfill U.S. Pat. No. 3,434,448 issued Mar. 25, 1969; McCormick U.S. Pat. No. 3,434,450 issued Mar. 25, 1969.

SUMMARY OF THE INVENTION The invention provides a hydraulic system which affords power tilting and trimming in such manner that tilting can occur without affecting the trim setting and such that upon return tilting the lower unit will return, without attention to trim by the operator, to the previously set trim position.

The invention also provides a hydraulic system as set forth in the preceding paragraph and which incorporates shock absorbing capacity so that, upon the striking of an underwater obstacle, energy will be dissipated and upon return tilting movement, the lower unit can be returned to the previously set trim position.

The invention further provides for an electrically operated hydraulic system which is selectively operable to provide either up or down power tilting or in or out power trim adjustments.

In accordance with the invention, there is provided, in association with an outboard motor propulsion or lower unit or in association with a stern drive propulsion or lower unit, a hydraulic tilt cylinder which functions to effect power tilting and which includes a piston provided with porting affording energy dissipation upon upward swinging of the propulsion unit in response to the striking of an underwater obstacle. Also in accordance with the invention, there is provided a hydraulic trim cylinder including an extensible ram which is engageable with a swivel bracket or other component to adjustably establish the trim setting. Although other arrangements are possible, in the disclosed construction, two tilt cylinders and two trim cylinders are employed.

Also in accordance with the invention, there is provided a hydraulic conduit and pump arrangement, as well as an electrical control system such that a single reversible pump provides pressure fluid under the same pressure to both the tilt and trim cylinders in response to actuation of a trim control switch and such that, upon actuation of a tilt control switch, hydraulic fluid is supplied only to the tilt cylinder, thus leaving the trim cylinderunaffected, so that upon return tilting, the swivel bracket or other component will return to the previously established trim position.

Also in accordance with the invention, the trim cylinders are arranged to take advantage ofa substantial moment arm with respect to the horizontal tilt axis so that trim adjustments can be effectively made under way and at high speeds. Thus, the trim cylinders are several times more powerful (because of moment arm consideration) then the tilt cylinders, notwithstanding employment of hydraulic fluid under the same pressure conditions.

Also in accordance with the invention, the power tilt and power trim features of the invention are employed as a supplement to the previously employed thrust pin which functions as a safety trimming device in case of failure of the hydraulic system.

One of the principal objects of the invention is the provision of a hydraulic system for tilting and trimming the vertical tiltable propulsion or lower unit of a marine propulsion device such as an outboard motor or stern drive unit.

Another principal object of the invention is the provision of a hydraulic system as indicated in the preceeding paragraph, which system includes a memory feature, i.e., in which power tilting can occur without affecting the trim setting and so that, accordingly, upon downward tilting, the propulsion unit will automatically return to the previously set trim position.

This feature is of substantial importance, as for instance, if an underwater obstacle were struck and the propulsion unit tilts rearwardly and upwardly, when using the construction disclosed herein, the propulsion unit can subsequently be power operated for return tilting movement to the pre-selected trim position with the foreknowledge that the propulsion unit will quickly and rapidly return to the previously set proper trim condition, thereby avoiding any necessity on the part of the operator to attend to trimming the propulsion unit.

Another of the principal objects of the invention is the provision of a hydraulic power tilting and trimming system in which trimming can be readily achieved when under way at high speeds and wherein power tilting can be accomplished independently of trimming and without affecting the previously set trim adjustment.

Another object of the invention is the provision of a hydraulic power tilting and trimming system which can be readily and economically manufactured and which will provide reliable service over a long and useful life.

Other objects and advantages of the invention will become known by reference to the following description and accompanying drawings.

DRAWINGS FIG. 1 is a fragmentary perspective view of an outboard motor embodying various of the features of the invention.

FIG. 2 is an enlarged fragmentary side elevational view of the outboard motor shown in FIG. 1 with the swivel bracket shown in a first trim position.

FIG. 3 is a view similar to FIG. 2 with the swivel bracket shown in a trim position which is angularly displaced rearwardly from the position shown in FIG. 2.

FIG. 4 is a view similar to FIG. 2 showing the location of the swivel bracket at the fully tilted position.

FIG. 5 is a schematic diagram of the hydraulic system incorporated in the outboard motor shown in FIG. 1.

FIG. 6 is a schematic view of the electrical control system incorporated in the outboard motor shown in FIG. 1.

GENERAL DESCRIPTION Shown in FIG. 1 is a marine propulsion device in the form of a fragmentarily illustrated outboard motor 11 which embodies various of the features of the invention and which is shown mounted on the transom 13 of a boat. As is conventional, the outboard motor 11 includes a clamp or transom bracket 17 which is connectable to the boat transom 13 and which journals a horizontally extending pintle or tilt pin 19. Carried by the pivot pin 19 is a tiltable assembly comprising a member or swivel bracket 21 which includes provision for rotatably mounting a king pin 23 in generally perpendicular relation to the horizontal tilt pin 19. As is conventional, the tiltable assembly also includes a propulsion or motor unit 27 which is connected to the king pin 23 and which includes a power head and a lower unit supporting a propeller, and which is steerable relative to the swivel bracket 21, as well as tiltable with the swivel bracket 21 relative to the transom bracket 17.

In general, the transom bracket 13 and swivel bracket 21 can be constructed, except as otherwise noted herein, in general accordance with the arrangement shown in the Conover US. Pat. No. 3,061,250 issued Oct. 30, 1962.

As is common, the transom bracket 17 includes a pair of transversely spaced rearwardly extending wings 29 having an arcuate series of aligned apertures 31 which extend at a common distance from the tilt pin 19 and which are adapted to selectively receive a thrust bolt 33 (See FIG. 2). In turn, the swivel bracket 21 includes a transversely extending concave pad 37 adapted to engage the thrust bolt 33 and to thereby establish the trim of the motor unit 27 relative to the boat and to the water and thereby also to provide for transmission to the boat of propulsive thrust generated by the propeller. Conventio'nally, changes in trim were achieved by moving the thrust bolt 33 from one set of aligned apertures 31 to another. Obviously, trim changes could not conveniently be made under way to meet changing wind and sea conditions or changing load conditions in the boat.

In accordance with the invention, in order to provide both power tilting and shock absorbing features, a first extensible hydraulic cylinder means 41 is pivotally connected between the transom bracket 17 and the swivel bracket 21. While other arrangements are possible, in the disclosed construction, the first hydraulic cylinder means 41 comprises a pair of hydraulic power tilt cylinders 43 and 47 which are essentially identically constructed and mounted, except for being transversely spaced. Only the cylinder 47 and its mounting will be described.

More specifically (as shown in FIG. 2), the hydraulic cylinder 47 is pivotally connected, at its lower end, to a piston rod 53 which, at its outer end, is pivotally mounted on a stud 57 extending from an upper part of the swivel bracket 21. As a consequence of the above described connection, the cylinder 47 pivots slightly during pivotal movement of the swivel bracket 21 rela tive to the transom bracket 17, but is nonetheless disposed with the axis of the cylinder in a generally upright position in generally parallel relation to the boat transom.

In order to provide for hydraulic actuation of the tilt cylinders 43 and 47 to afford power tilting of the connected propulsion or motor unit 27 and swivel bracket 21 in both directions between a normal running position and a raised or elevated position which can be angularly spaced from the running position anywhere from about 40 to about hydraulic fittings 59 and 61 are respectively provided at the upper and lower ends of each of the cylinders 43 and 47 whereby to constitute each cylinder a double acting cylinder.

In order that the hydraulic cylinder can also function as a shock absorber in response to violent striking of an underwater object, the piston 51 is provided with porting 63 in the form of one-way spring controlled check valve or valves which will open to permit restricted fluid flow, and thereby to absorb or dissipate energy,

when the pressure in the fluid above the piston 51 increases above a predetermined value in response to attempted rearward and upward tilting movement of the propulsion or motor unit 27 and connected swivel bracket 21 consequent to the violent striking of an underwater obstacle. The springs associated with the check valves are designed to keep the check valves closed under normal cylinder pressures produced by a reversible electric pump 71 which is designed to be mounted remotely from the cylinders 43 and 47 and preferably inside of the boat.

The pump 71 includes two outlet ducts or ports 73 and 77 and is constructed and is selectively operable so that, in response to rotation in one direction, pressure fluid is supplied to one of the outlet ports 73 and 77-and the other outlet port is connected to a sump or source of fluid, and in response to rotation in the opposite direction, pressure fluid is supplied to the other outlet port and the first mentioned port is connected to the sump or source of pressure fluid. Such pumps 71 are well known in the art and need not be further described.

Also in accordance with the invention, and in order to provide power trim independently of the power tilting, i.e., to permit power tilting without affecting the trim setting, there is provided a second extensible hydraulic cylinder means 81 connected to the transom bracket 17 and including an extensible ram engageable with the swivel bracket. While other constructions can be employed, in the disclosed construction, such second extensible hydraulic cylinder means comprises a pair of hydraulic trim cylinders 83 and 87 which are essentially identically constructed and mounted except for being transversely spaced. Accordingly, only the hydraulic cylinder 87 will be described.

More particularly, the hydraulic cylinder 87 is provided as a part of a unitary casting or member 89 which form both cylinders 83 and 87, which provide various conduits or ducts, still to be described, and which is adapted to be mounted on the lower part of the.

transom bracket 17. Carried in the cylinder 87 is a piston 91 which is connected to an .extensible part or ram 93 extending outwardly of the cylinder 87 for abutting engagement with a cooperating pad or ear 97 on the swivel bracket 21. The cylinder 87 is essentially double acting and, as shown, is mounted on the transom bracket in such manner that the ram 93 or axis of the cylinder extends at an angle of about 60 degrees to the transom. Accordingly, the perpendicular distance from the axis of the trim cylinders 83 and 87 to the tilt pin 19 is substantial and is. several. times greater than the maximum perpendicular distance to the tilt pin 19 from the axis of the tilt cylinders 43 and 47. In the specifically disclosed construction, the perpendicular distance from the tilt pin 19 to the trim cylinder axes is six times the maximum perpendicular distance from the tilt pin 19 to the tilt cylinder axes.

Means (See FIG. 5) in the formof a hydraulic eonduit system 11 1 is provided for connecting the pump 71 to the cylinders 43, 47, 83, and 87. In addition, means (See FIG. 6) in the form of an electrical control system 113 is provided for actuating the pump 71v and controlling the hydraulic conduit system 1 11 so as to selectively afford power trimming and power tilting, and so as to afford tilting of the motor unit upwardly from a selected trim position either in response to hydraulic action or in response to striking of an underwater obstacle and so that, upon return tilting, the motor or propulsion unit 27 will return to the previously preselected trim position.

As can be seen from FIG. 5, the trim cylinders 83 and 87 are hydraulically connected in parallel with each other and the tilt cylinders 43 and 47 are also hydraulically connected in parallel with each other. As can also be seen from FIG. 5, the tilt cylinders 43 and 47, as a group, are connected to the hydraulic pump 71 in parallel with the connection of the trim cylinders 83 and 87, as a group, to the pump 71. More specifically, the hydraulic conduit system 111 includes a first conduit'l17 which extends from the pump outlet port 73 and communicates with a pressure relief valve 119, and which includes a first branch 121 connected to one end of the tilt cylinders 43 and 47, and. a second branch 123 connected to one end of the trim cylinders 83 and 87. The hydraulic conduit system 111 also includes a second conduit 127 which extends from the pump outlet port 77 and communicates with a pressure relief valve 129, and which includes a first branch 131 connected to the other end of the tilt cylinders 43 and 47 and a second branch 133 connected to the other end of the trim cylinders 83 and 87.

In order to permit operation of the tilt cylinders 43 and 47 without operating the trim cylinders 83 and 87, one of the branch conduits, i.e., in the disclosed construction, the branch conduit 133, includes a normally closed solenoid operated valve 137.

As shown in FIG. 6', the electrical control system 113 includes a motor 139 which is included in the pump 71, as well as a tilt control switch 141 and a trim control switch 143.

The tilt switch 141 constitutes a single pole double throw switch operable to selectively provide for operating the pump motor 139 in either direction. More particularly, the tilt switch 141 is operable through respective up and down relays 147 and 149 to provide for associated operation of the pump motor 139.

Specifically, the relays 147 and 149 are each connected to a ground 151, such as the frame of the pump motor, and are selectively connectable through the tilt control switch 141 to a battery 153. r,

The pump motor 139 is connected through the relays 147 and 149 to a pump battery 157 so that pump operation in one direction occurs in response to energizing of the up" relay 147 and so that pump operation in the other direction occurs in response to energizing of the down" relay 149.

The trim control switch 143 comprisesa double pole double throw switch which is connected to the battery 153 and to the up" and down" relays 147 and 149, as well as to a solenoid 1-59 operatively associated with the normally closed valve 137, which solenoid 159 is.

also connected to ground. 151. In operation, the trim control switch 143' is operable to selectively provide for operation of the pump motor 139 in either the up or down direction and to simultaneously energize the solenoid 159 so as to open the branch conduit 133 and to afford hydraulic flow relative to the trim cylind'ers83 and 87 so as to thereby extend or retract the rams 93 as may be desired, notwithstanding under way operation of the boat at high speeds.

Also in operation, when the tilt control switch 141 is actuated, hydraulic fluid is supplied to the tilt cylinders 43 and 47 to raise or lower the propulsion or motor unit 27. However, actuation of the tilt control switch 141 is ineffective to energize the solenoid 159 and, accordingly, the rams 93 do not change position. Thus, upon down tilting of the propulsion or motor unit 27 subsequent to the striking of an underwater obstacle or in response to actuation of the tilt control switch 141, the motor unit 27 will come to rest at the trim position previously established by the rams 93.

Thus, it is clear, that tilting of the motor unit 27 can occur in reference to a preselected trim position which is not disturbed as a consequence of such tilting.

When the trim control switch 143 is actuated, hydraulic fluid is supplied to both the tilt cylinders 43 and 47 and to the trim cylinders 83 and 87 to cause adjustment in the position of the rams 93 and accompany.- ing tilting of the motor unit 27. Such adjustment of the ram position selectively establishes the desired trim.

It is noted that the moment arm or perpendicular distance to the tilt pin 19 from the axis of the trim cylinders 83 and 87 is several times the moment arm to the tilt pin 19 from the axis of the tilt cylinders 43 and 47 and, as a consequence, even though all cylinders 43, 47, 83, and 87 are subject to the same pressure, the trim cylinders 83 and 87 are several times more effective in displacing the motor unit 27 about the horizontal tilt axis. As a consequence of the substantial moment arm associated with the trim cylinders 83 and 87, the trim cylinders 83 and 87 are effective to change the trim of the motor unit 27 even when under way under full throttle conditions. 7

It should also be noted the disclosed construction continues the use of the thrust bolt or pin 33 which serves a safety function, limiting vertical swinging movement of the propulsion unit and connected swivel bracket toward the transom bracket in the unlikely event of a hydraulic failure. As a consequence, even if there is hydraulic failure, the disclosed construction retains the conventional capability for trim adjustment.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. A marine propulsion device comprising a first bracket adapted to be attached to a boat transom, a tiltable assembly comprising a second bracket connected to said transom bracket for vertical swinging movement about a horizontal axis, and a propulsion unit connected to said second bracket for swinging movement relative to said second bracket about anaxis transverse to said horizontal axis, a first extensible hydraulic cylinder means, means pivotally connecting said first extensible hydraulic cylinder means to said first bracket and to said tiltable assembly, a second extensible hydraulic cylinder means having an extensible part, means connecting said second extensible hydraulic cylinder means to one of said first bracket and said tiltable assembly with said extensible part being positioned for engagement with the other of said first bracket and said tiltable assembly, an electrically operated hydraulic pump, and conduit means hydraulically communicating said first and second extensible hydraulic cylinder means in parallel relation to said hydraulic pump and including an electrically operated normally closed valve controlling communication between said second extensible hydraulic cylinder means and said hydraulic pump independently of the communication between said first extensible hydraulic cylinder means and said hydraulic pump.

2. A marine propulsion device in accordance with claim 1 wherein said device is an outboard motor.

3. A marine propulsion device in accordance with claim 2 including a pivot connecting said second bracket to said first bracket and wherein said second hydraulic cylinder means has an axis at a greater perpendicular distance from said pivot than the maximum perpendicular distance from said pivot to the axis of said first hydraulic cylinder means.

4. A marine propulsion device in accordance with claim 3 wherein said perpendicular distance from the axis of said second hydraulic cylinder means to said pivot is more than double the perpendicular distance from said pivot to the axis of said first hydraulic cylinder means.

5. A marine propulsion device in accordance with claim 2 wherein said tiltable assembly is pivotal upwardly from a normal operating position relative to said first bracket through an arc of at least about 45 and wherein said second hydraulic cylinder means is disengaged from the other of said first bracket and tiltable assembly prior to pivotal movement of said tiltable assembly from the normal operating position through an arc of about 30.

6. A marine propulsion device in accordance with claim 2 wherein said first hydraulic cylinder means comprises a hydraulic shock absorber including a cylinder, a piston movable in said cylinder, and means affording hydraulic flow from one side of said piston to the other in response to sudden upward movement of said tiltable assembly from the normal operating running position.

7. A marine propulsion device in accordance with claim 2 wherein said second hydraulic cylinder means comprises a cylinder fixed rigidly relative to said first bracket, a piston movable in said cylinder, and wherein said extensible part comprises a ram extending fixedly from said piston and through one end of said cylinder.

8. An outboard motor comprising a transom bracket, a second bracket connected to said transoirn bracket for vertical swinging movement about a horizontal axis and adapted to support a propulsion unit for swinging movement relative to said second bracket about an axis transverse to said horizontal axis, a first extensible hydraulic cylinder means, means pivotally connecting said first extensible hydraulic cylinder means to said transom bracket and to said second bracket, a second extensible hydraulic cylinder means having an extensible part, means connecting said second extensible hydraulic cylinder means to said transom bracket with said extensible part positioned for engagement with said second bracket, an electrically operated hydraulic pump, conduit means hydraulically communicating said first and second extensible hydraulic cylinder means in parallel relation to said hydraulic pump and including an electrically operated normally closed valve controlling communication between said second extensible hydraulic cylinder means and said hydraulic pump independently of the communication between said first extensible hydraulic cylinder means and said hydraulic pump, a tilt control switch electrically connected to said hydraulic pump for actuating said hydraulic pump in response to operation of said tilt control switch, and a trim control switch electrically connected to said hydraulic pump and to said normally closed valve for actuating said hydraulic pump and for opening said valve in response to operation of said trim control switch.

9. An outboard motor in accordance with claim 8 wherein said hydraulic pump is a reversible pump and includes first and second outlet ports and wherein said conduit means connects each end of each of said first and second extensible hydraulic cylinder means to said outlet ports of said pump to provide for power operation in opposing directions.

10. An outboard motor in accordance with claim 8 wherein said transom bracket includes a series of apertures at a common radius from said horizontal axis and further including a thrust bolt removably received in one of said apertures and wherein said second bracket includes a portion engageable with said thrust bolt when permitted by the location of said extensible part.

11. A marine propulsion device in accordance with claim 1 wherein said second extensible hydraulic cylinder means includes two cylinders and respective pistons in each of said cylinders.

12. A marine propulsion device in accordance with claim 1 including a trim control switch electrically connected to said hydraulic pump and to said normally closed valve for actuating said hydraulic pump and for opening said valve in response to operation of said trim control switch.

13. A marine propulsion device in accordance with claim 1 including a tilt control switch electrically connected to said hydraulic pump for actuating said hydraulic pump in response to operation of said tilt control switch, and a trim control switch electrically connected to said hydraulic pump and to said normally closed valve for actuating said hydraulic pump and for opening said valve in response to operation of said trim control switch 14. A marine propulsion device in accordance with claim 1 wherein said hydraulic pump is a reversible pump and includes first and second outlet ports and wherein said conduit means connects each end of each of said first and second extensible hydraulic cylinder means to said outlet ports of said pump to provide for power operation in opposing directions and wherein said normally closed valve controls fluid flow to the end of sald second extensible cylinder means opposite from said extensible part.

15. A marine propulsion device in accordance with claim 1 wherein said first bracket includes a series of apertures at a common radius from said horizontal axis and further including a thrust bolt removably received in one of said apertures and wherein said tiltable as sembly includes a portion engageable with said thrust bolt when permitted by the location of said extensible part.

16. A marine propulsion device comprising a first bracket adapted to be attached to a boat transom, a tiltable assembly comprising a second bracket connected to said transom bracket for vertical swinging movement about a horizontal axis, and a propulsion unit connected to said second bracket for swinging movement relative to said second bracket about an axis 'tioned for engagement with the other of said first bracket and said tiltable assembly, an electrically operated hydraulic pump, and conduit means hydraulically communicatingbetween said pump and each of said first and second extensible hydraulic means and including means for operating said first extensible hydraulic cylinder means independently of said second extensible hydraulic cylinder means. 

1. A marine propulsion device comprising a first bracket adapted to be attached to a boat transom, a tiltable assembly comprising a second bracket connected to said transom bracket for vertical swinging movement about a horizontal axis, and a propulsion unit connected to said second bracket for swinging movement relative to said second bracket about an axis transverse to said horizontal axis, a first extensible hydraulic cylinder means, means pivotally connecting said first extensible hydraulic cylinder means to said first bracket and to said tiltable assembly, a second extensible hydraulic cylinder means having an extensible part, means connecting said second extensible hydraulic cylinder means to one of said first bracket and said tiltable assembly with said extensible part being positioned for engagement with the other of said first bracket and said tiltable assembly, an electrically operated hydraulic pump, and conduit means hydraulically communicating said first and second extensible hydraulic cylinder means in parallel relation to said hydraulic pump and including an electrically operated normally closed valve controlling communication between said second extensible hydraulic cylinder means and said hydraulic pump independently of the communication between said first extensible hydraulic cylinder means and said hydraulic pump.
 2. A marine propulsion device in accordance with claim 1 wherein said device is an outboard motor.
 3. A marine propulsion device in accordance with claim 2 including a pivot connecting said second bracket to said first bracket and wherein said second hydraulic cylinder means has an axis at a greater perpendicular distance from said pivot than the maximum perpendicular distance from said pivot to the axis of said first hydraulic cylinder means.
 4. A marine propulsion device in accordance with claim 3 wherein said perpendicular distance from the axis of said second hydraulic cylinder means to said pivot is more than double the perpendicular distance from said pivot to the axis of said first hydraulic cylinder means.
 5. A marine propulsion device in accordance with claim 2 wherein said tiltable assembly is pivotal upwardly from a normal operating position relative to said first bracket through an arc of at least about 45* and wherein said second hydraulic cylinder means is disengaged from the other of said first bracket and tiltable assembly prior to pivotal movement of said tiltable assembly from the normal operating position through an arc of about 30*.
 6. A marine propulsion device in accordance with claim 2 wherein said first hydraulic cylinder means comprises a hydraulic shock absorber including a cylinder, a piston movable in said cylinder, and means affording hydraulic flow from one side of said piston to the other in response to sudden upward movement of said tiltable assembly from the normal operating running position.
 7. A marine propulsion device in accordance with claim 2 wherein said second hydraulic cylinder means comprises a cylinder fixed rigidly relative to said first bracket, a piston movable in said cylinder, and wherein said extensible part comprises a ram extending fixedly from said piston and through one end of said cylinder.
 8. An outboard motor comprising a transom bracket, a second bracket connected to said transom bracket for vertical swinging movement about a horizontal axis and adapted to support a propulsion unit for swinging movement relative to said second bracket about an axis transverse to said horizontal axis, a first extensible hydraulic cylinder means, means pivotally connecting said first extensible hydraulic cylinder means to said transom bracket and to said second bracket, a second extensible hydraulic cylinder mEans having an extensible part, means connecting said second extensible hydraulic cylinder means to said transom bracket with said extensible part positioned for engagement with said second bracket, an electrically operated hydraulic pump, conduit means hydraulically communicating said first and second extensible hydraulic cylinder means in parallel relation to said hydraulic pump and including an electrically operated normally closed valve controlling communication between said second extensible hydraulic cylinder means and said hydraulic pump independently of the communication between said first extensible hydraulic cylinder means and said hydraulic pump, a tilt control switch electrically connected to said hydraulic pump for actuating said hydraulic pump in response to operation of said tilt control switch, and a trim control switch electrically connected to said hydraulic pump and to said normally closed valve for actuating said hydraulic pump and for opening said valve in response to operation of said trim control switch.
 9. An outboard motor in accordance with claim 8 wherein said hydraulic pump is a reversible pump and includes first and second outlet ports and wherein said conduit means connects each end of each of said first and second extensible hydraulic cylinder means to said outlet ports of said pump to provide for power operation in opposing directions.
 10. An outboard motor in accordance with claim 8 wherein said transom bracket includes a series of apertures at a common radius from said horizontal axis and further including a thrust bolt removably received in one of said apertures and wherein said second bracket includes a portion engageable with said thrust bolt when permitted by the location of said extensible part.
 11. A marine propulsion device in accordance with claim 1 wherein said second extensible hydraulic cylinder means includes two cylinders and respective pistons in each of said cylinders.
 12. A marine propulsion device in accordance with claim 1 including a trim control switch electrically connected to said hydraulic pump and to said normally closed valve for actuating said hydraulic pump and for opening said valve in response to operation of said trim control sWitch.
 13. A marine propulsion device in accordance with claim 1 including a tilt control switch electrically connected to said hydraulic pump for actuating said hydraulic pump in response to operation of said tilt control switch, and a trim control switch electrically connected to said hydraulic pump and to said normally closed valve for actuating said hydraulic pump and for opening said valve in response to operation of said trim control switch
 14. A marine propulsion device in accordance with claim 1 wherein said hydraulic pump is a reversible pump and includes first and second outlet ports and wherein said conduit means connects each end of each of said first and second extensible hydraulic cylinder means to said outlet ports of said pump to provide for power operation in opposing directions and wherein said normally closed valve controls fluid flow to the end of saId second extensible cylinder means opposite from said extensible part.
 15. A marine propulsion device in accordance with claim 1 wherein said first bracket includes a series of apertures at a common radius from said horizontal axis and further including a thrust bolt removably received in one of said apertures and wherein said tiltable assembly includes a portion engageable with said thrust bolt when permitted by the location of said extensible part.
 16. A marine propulsion device comprising a first bracket adapted to be attached to a boat transom, a tiltable assembly comprising a second bracket connected to said transom bracket for vertical swinging movement about a horizontal axis, and a propulsion unit connected to said second bracket for swinging movement relative to said second bracket about an axis transverse to said horizontal axis, a first extensible hydraulic cylinder means, means pivotaLly connecting said first extensible hydraulic cylinder means to said first bracket and to said tiltable assembly, a second extensible hydraulic cylinder means having an extensible part, means connecting said second extensible hydraulic cylinder means to one of said first bracket and said tiltable assembly with said extensible part being positioned for engagement with the other of said first bracket and said tiltable assembly, an electrically operated hydraulic pump, and conduit means hydraulically communicating between said pump and each of said first and second extensible hydraulic means and including means for operating said first extensible hydraulic cylinder means independently of said second extensible hydraulic cylinder means. 